August 11, 2017 by Jill Anderson, in CBD (Cannabidiol)

In our previous 3-part series, we revealed why researchers believe that cannabidol (CBD) has huge potential for the treatment of bone health. Not only can it potentially enhance fracture healing and promote bone growth, CBD can also be an effective future treatment for osteoporosis (literally “porous bones”) and arthritis (pain and/or inflammation in joints).

But in a recent 2016 study, a team of researchers from the U.K. investigated possible associations between recreational cannabis use and bone health in humans and came to a completely different conclusion – albeit with smoked cannabis instead of just an extraction of CBD.

They approached 284 individuals aged ≥ 18 years who were attending a general practice surgery for routine appointments between November 2011 and March 2013. Individuals were invited to take part if they had a history of current or previous use of tobacco or cannabis. After providing written informed consent, participants completed a questionnaire in which details were collected on demographics, smoking, and alcohol intake, cannabis use, use of other illegal drugs, dietary calcium intake by food frequency, fracture history, family history of hip fracture, participation in sports, whether the subjects were weight bearing for more than 4 hours a day, and medical history. Participants were also invited to undergo bone densitometry and to provide a blood sample for biochemical analysis.

Once they collected the questionnaire, the researchers divided the individuals into groups of moderate cannabis users (n = 56) and heavy users (n = 144), depending on whether they reported fewer or more than 5000 cannabis smoking episodes during their lifetime. The control subjects were comprised of 114 cigarette smokers.

After measuring their bone mineral density and other biochemical markers, they concluded that bone mineral density was significantly lower in heavy cannabis users when compared with controls at the lumbar spine, femoral neck, and total hip. In addition to reduced bone density at all sites measured, heavy cannabis users also had reduced body mass index, high bone turnover (refers to the total volume of bone that is both resorbed and formed over a period of time), and an increased rate of fractures.

Surprisingly, this study appears to directly contradict previous research regarding cannabinoids and bone health. More specifically, they linked heavy cannabis use to reduced bone density while other studies have shown that cannabinoids found in cannabis actually promotes bone growth.

So what gives? Has all the previous research been incorrect or were there flaws in this particular study?

Upon closer inspection, we can begin to find out what these results really mean.

What we don’t know

Critically important to note in this study is that although the authors utilized techniques including regression and mediation analysis to correct for potential confounding factors, they stressed that the results obtained do not infer a cause-and-effect relationship.

In other words, it’s equally plausible that heavy cannabis use may be related to lower bone density because people with lower bone density prefer to smoke a lot of cannabis.

Another important factor is the data that was collected.

There were 284 participants in the study which seems like a decent sample size. However, about two-thirds of the heavy cannabis users reported that they had also taken other illegal drugs.

Dietary calcium intake was higher in heavy cannabis users than in controls.

BMI was significantly lower in heavy cannabis users than in controls.

And the proportion of heavy cannabis users who reported standing for more than 4 hours a day was lower than the control group.

Any or all of these factors could’ve affected the results.

Another issue is that the data was collected through questionnaires so there was no way to verify the accuracy of each subject’s answers. More importantly, there was no data collected on each subject’s marijuana usage and habits except whether they reported fewer or more than 5000 cannabis smoking episodes during their lifetime.

What type of cannabis did these subjects smoke? How much and how frequently did they smoke? What was the cannabinoid content of the cannabis? Were they smoking high-CBD strains, low-CBD strains, etc…?

Finally, the study also disclosed a conflict of interest. One of the authors, Stuart H. Ralston from the University of Edinburgh, is the inventor of a patent concerning the use of cannabinoid receptor ligands as treatments for osteoporosis and other bone diseases.

If this author’s invention directly competes with cannabis as a potential treatment for osteoporosis and other bone diseases, then does he stand to benefit from results that point to cannabis’ deleterious effects?

All of these factors need to be taken into account when evaluating the findings reported in this study. In this instance, the researchers’ use of data from questionnaires to infer that heavy cannabis use could be a potential cause of low bone mineral density, increased bone turnover, and predisposition to fractures didn’t actually provide any clear answers and in fact, only raised more questions.

A newer study with different results

A different example of research is a more recent study by researchers from the General Hospital of the People’s Liberation Army in Beijing.

Published in the European Journal of Pharmacology, this study investigated the therapeutic effect of CBD, the non-psychoactive component in cannabis, on sublesional bone loss in a rat model of spinal cord injury (SCI).

Patients with spinal cord injury undergo severe loss of bone mineral below the level of injury. These individuals are at high risk of developing osteoporosis and possibly bone fractures. In fact, about 80% of individuals with chronic spinal cord injury have either osteopenia or osteoporosis.

In this study, adult male Wistar rats were exposed to surgical transection (cutting) of the spinal cord and treated with CBD for 14 consecutive days.

The administration of CBD was associated with elevated serum levels of osteocalcin (a calcium-binding substance produced by osteoblasts that is essential to bone mineralization and can be used as a biomarker for osteoporosis), reduced the serum levels of collagen type I cross-linked C-telopeptide (a biomarker in the serum to measure the rate of bone turnover), and enhanced bone mineral density of tibiae and femurs.

Treatment of SCI rats with CBD also enhanced bone volume, trabecular thickness, and trabecular number, and reduced trabecular separation in proximal tibiae (the inner and typically larger of the two bones between the knee and the ankle), and increased ultimate compressive load, stiffness, and energy to max force of the femur shaft.

In contrast to the previous study, the materials and methods utilized were standard for this type of study and the researchers reported no conflict of interest.

Be cautious with your research

Here at IwantmyCBD.org, we try to remain as objective as possible in bringing our readers the most up-to-date and relevant information backed by sound science. We also urge our readers to always be cautious and to be careful of potential research bias that can possibly skew a study’s results.

Although it is practically impossible to completely eliminate research bias from science, actively trying to identify and avoid biased research can make a huge difference in our understanding of the issues at hand. When readers can critically and independently review scientific literature, it can help them reach better informed decisions. In the case of CBD as medicine – where evidence-based facts are absolutely essential – elimination of research bias is of even greater importance and should be considered when evaluating every study.

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